1. Field of the Invention
The present invention relates to a liquid crystal display, and more particularly, to a liquid crystal display having reduced power consumption.
2. Description of the Prior Art
As an information-oriented society has been developing in recent years, electronic devices such as personal computers and Personal Digital Assistants (PDAs) are widely used. Portable electronic devices that are suitable to be used in an office and outdoors are in demand, and thus they continue to become smaller and lighter. Liquid crystal displays are widely used to meet the requirements for producing battery powered smaller, lighter and lower power consuming portable electronic devices.
Liquid crystal displays can be categorized as reflective liquid crystal display and transmissive liquid crystal display in accordance with a travel path of light used for image display. Reflective liquid crystal display reflects a light beam incident on the front side of a liquid crystal panel by the rear side of the liquid crystal panel and visualizes an image by the reflected light, and transmissive liquid crystal display visualizes an image by the transmitted light from a light source (e.g., backlight) provided on the rear side of a liquid crystal panel to the front side of the liquid crystal panel. The visibility of a reflective liquid crystal display is poor because the quantity of reflected light is not constant due to varying environmental conditions, and thus a transmissive color liquid crystal display using a color filter is generally used as a display device of a personal computer displaying full-color.
Liquid crystal displays can also be categorized into TN (Twisted Nematic) liquid crystal displays and STN (Super-Twisted Nematic) liquid crystal displays in accordance with the driving method, and there are an active matrix display method using a switching element and a TN liquid crystal and a passive matrix display method using a STN liquid crystal.
A liquid crystal display using an active matrix drive method is widely used as a color display. Thin film transistors, which are included in a plurality of liquid crystal cells and used to switch and supply data voltages to the liquid crystal cells, are provided on a liquid crystal panel of an active matrix liquid crystal display. The liquid crystal cells are located at crossings of data lines and gate lines, and the thin film transistors are positioned on the crossings. The display quality of the active matrix liquid crystal display is better than that of a passive matrix liquid crystal display. However, because the active matrix liquid crystal display operates a driving circuit to operate the thin film transistors of the liquid crystal cells and transfer voltages, power consumption of the active matrix liquid crystal display is increased.